Method for closing and sealing containers



Nov. 26, 1963 w. E. MEISSNER "METHOD FOR CLOSING AND SEALING CONTAINERSFiled April 10, 1961 United States Patent 3,111,796 liiETI-IGD FURCLUSING AND SEAMNG CQNTAENERE? William E. Meissner, Devon, Pa, assignor,by mesne assignments, to FMC @erporation, San .iose, Calif, acorporation of Delaware Filed Apr. 10, 1961, st. No. 192,611 8 Claims.(Cl. 53-38) The invention rel-ates to an improved method for closing andsealing containers.

in packing articles of flowable materials in preformed flexible orcollapsible containers, such as bags, a common practice is to merelyclose the open end of the container as by folding or twisting and thenfix the same with a tape, cord, or metal fastener. in applications wherea more secure or perhaps leakproof closure is required, the containermay be heat-sealed or alternately sealed with an adhesive compound.Heat-sealing procedures of course require that the container be formedof or at least coated with a thermoplastic material and often demandexacting operating conditions to facilitate the formation of a strongand uniform bond without damaging either the container or its contents.Employing adhesive compounds, on the other hand, entails the use ofvarious forms of applicators which do not insure an even distribution ofthe adhesive compound to all areas of the surfaces to be coated.Accordingly, a primary object of this invention is to provide a new orimproved and more satisfactory method for closing and sealing preformedcontainers.

Another object is the provision of an improved method for closing andsealing a collapsible container by rupturing a bubble of tackyfilm-forming material at least partially within the open end of thecontainer as that portion of the container is urged into a collapsedposition.

Still another object is to provide an improved method wherein at leastone mass of tacky film-forming material is expanded into the form of abubble within the open end of a container and then ruptured to provide auniform and continuous tacky lining on the adjacent surfaces of thecontainer.

A further object is the provision of a method wherein at least one massor gob of tacky film-forming material is inflated into the form of abubble within and/ or across the open end of the container and thenruptured as portions of the container itself are urged into collapsedposition to provide an adhesive lining on the adjacent containersurfaces.

These and other objects and advantages of the invention will becomeapparent from the following description and ccompanying drawing inwhich:

FIGURE 1 is a diagrammatic view illustrating a mass of film-formingmaterial being initially expanded into the form of a bubble within theopen end of a container;

FIGURE 2 is a View similar to FIGURE 1 showing a bubble of film-formingmaterial as it is deformed during the initial collapse of the containeropen end;

FIGURE 3 illustrates the container of FIGURE 2 as the bubble offilm-forming material is ruptured during collapse of the open end of thecontainer;

FIGURE 4 is a view similar to FIGURE 1 illustrating the inflation of amass of film-forming material within the open end of a container havingnon-self supporting flexible Walls;

FIGURE 5 shows the container of FIGURE 4 as closed and sealed by atwisting of a portion thereof;

FIGURE 6 is a view similar to FEGURE 1 illustrating a modified procedurefor applying adhesive to a container having an elongated open end; and

FIGURE 7 is a view similar to FIGURE 6' illustrating a still furthermodified procedure for applying adhesive to a container having anelongated open end.

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In general, the present invention relates to closing and sealing ofcontainers, and particularly to a method wherein a mass or gob offilm-forming material is suspended within the open end of a container,expanded into the form of a bubble, and then ruptured concomitantly asthe open end of the container is collapsed to provide a continuous anduniform adhesive coating along the adjacent internal surfaces of thecontainer walls. During the collapse of the open end of the container,and prior to rupture of the expanded bubble of film-forming material,the bubble is deformed into conformity with the adjacent surfaces of thecontainer walls and thereby progressively lines the same with acontinuous adhesive coating which remains in place after bubble rupture.

In accordance with a modified procedure of the present invention, a massof film-forming material may be eX' panded into the form of a bubbleconcomitantly as the mass of film-forming material is moved relative toor across the open end of a container. As a further alternative, aseries of bubbles of film-forming material may be expanded within theopen end of a container so as to together cooperate to adhesively lineor coat the internal surfaces of the container walls as the open endthereof is collapsed. These particular procedures are well adapted forsealing containers having relatively wide or elongated open ends andprovide for a continuous and uniform adhesive coating along the internalsurfaces of the container walls in much the same manner as heretoforementioned.

Control over the areas of the container walls coated with the adhesivefilm-forming material may be achieved by selectively positioning theexpanded bubble or bubbles of film-forming material relative to the openend of the container. An alternative and preferred procedure forachieving more accurate control however, is to vary the size of theexpanded bubble or number of bubbles so that L16 internal surfaces ofthe container walls, or at least the major portions thereof, engage withthe expanded bubble or bubbles of film-forming material only during theterminal stage of the container collapsing operation.

The thickness of the adhesive coating applied to the internal surfacesof the container walls can be regulated by varying the amount offilm-forming material, the degree of inflation thereof or the number andsize of the bubbles of film-forming material employed. Thus, where arelatively thick adhesive coating is desired, a relatively large mass offilm-forming material may be initially applied, or alternatively,additional film-forming material may be supplied concomitantly with theinflation thereof into a bubble form.

A wide variety of film-forming materials which are of a tacky oradhesive character when rendered plastic or flowable may be employed inthe practice of the present invention. Preferred types include thesynthetic linear polymers of thermoplastic character and the elastomerictypes. Examples include vinyl resins, such as polyvinyl acetate,copolymers of vinyl chloride and vinyl acetate, copolymers ofacrylonitrile and vinyl acetate, polyacrylonitrile and copolymers ofacrylonitrile With vinyl chloride, vinyl acetate, methacrylonitrile, andso forth, polyethylene, linear superpolymers of the polyester of nylon(polyamide) type, polyvinyl butyral, polyvinyl alcohols, polyvinylethers; elastomeric types may include neoprene, polymers of chloroprene,copolymers of butadiene with styrene or acrylonitrile, polyisobutylene,and so forth. It is to be understood that the mentioning of theseparticular materials is not intended to limit the invention thereto butmerely to illustrate the wide variety of film-forming materials that canbe used in carrying out the invention.

The film-forming material may be converted into a fiowable mass or gobby fusion or by the incorporation of plasticizers or solvents capable ofdissolving or dispersing the material. Thus, any of the thermoplasticmaterials may be heated to fusion after which the inflating medium maybe introduced into a gob thereof, preferably at the same temperature asthe fused material. If necessary, the temperature of fusion may belowered by the incorporation of a plasticizer either of solid or liquidcharac er. When plasticizers or solvents are incorporated into theplastic material to form the gob, the plasticizer or solvent ispreferably non-reactive with the inflating medium. The cooling of thefused plastic mass, with or without plasticizers, is effected as theexpanded bubble or envelope of film-forming material progressively linesthe adjacent internal surfaces of the container walls during thecollapse of the containcr open end.

Volatile solvents may be employed for dissolving or dispersing thefilm-forming material so that a gob thereof may be formed at roomtemperature and expanded, with the setting or coagulation of theexpanded bubble, after application to the container walls, occurring byvolatilize- -tion of the solvent. Known solvents and plasticizers may beemployed, the selection depending upon the particular filmiormingmaterial to be used. Thus, acetone or dioxane may be used for vinylacetate or copolymers of vinyl acetate or vinyl chloride oracrylonitrile. The concentration of the film-forming material, when asolution thereof is used, is preferably as great as possible and islimited only by the necessity that the plastic mass be capable ofexpanding under the pressure of the inflating medium, yet be of areasonably viscous and coherent plastic character so as to be capable ofsupporting its own weight.

The inflating medium may be air or other gas which is non-reactive withthe film-forming material or the packaged product. As heretoforementioned, the inflating medium is preferably heated when delivered intothe gob of film-forming material to prevent premature setting thereof.In sealing large containers or receptacles, it may be further desirableto effect sealing with the container itself being heated or disposedwithin a heated chamber. As more fully described hereafter, a gob offilm-forming material may be partially inflated as a bu bble within theopen end of a container, after which the container and bubble offilm-forming material may be subjected to vacuum conditions. With thisprocedure, air and other gases may be removed from the packaged productconcomitantly as the bubble itself expands into engagement with theadjacent container walls.

The teachings of the present invention are applicable to sealingcontainers of various types in which portions of the container itselfare collapsed to effect closing. The containers may be formed ofgenerally rigid or stiif materials in which preformed crease lines areprovided to facilitate collapse of the open end of the container, as forexample as in the case of conventional milk cartons, or may be made offlexible materials such as paper, fabrics, plastic films, regeneratedcellulose, and the like. If desired, the material forming the containermay be fluid-tight or may be lined to form a fluid-tight surface. Forthe sake of simplicity and ease of description, the method and apparatusof the present invention will hereafter be described as applied to theclosing and sealing of conventional paper bags after the material orproduct to be packaged is disposed therein.

For a more detailed description of the invention, refercnce is initiallymade to FlGURES 1-3 of the drawing which illustrate a sequence ofoperations carried out in sealing a conventional paper container or bag15 after the material or product to be packaged is disposed therein, asindicated by broken lines at 16. Initially, the container 15 ispositioned with its open end directly below a nozzle 17 which includes apair of spaced concentric or telescoped tubes 19 and 21. The uppermostend of the tube 19 is connected to a supply of flowable film-formingmaterial, with means being provided for periodically delivering thefilm-forming material. The tube 215. is similarly connected to asuitable pump or pressurized tank for delivering an inflating medium,such as air, in accordance with a predetermined flow pattern. Either thenozzle -17 or a support for the bag 15 Or both is mounted for verticalmovement by suitable means, not shown, to facilitate desired positioningof the free end of the nozzle relative to the open end of the bag 15 atthe start of operations.

In sealing the bag 15, the nozzle 17 is initially located in a desiredposition relative to the open end of the bag, after which plasticfilm-forming material is supplied through the tube 17 to form a gobthereof at the tip of the nozzle 17 where it covers the adjacent end ofthe tube 21, as shown by broken lines 23. The infiating medium is thensupplied through the tube 21 to effect a continuous expansion of the gobof plastic filmforming material into the form of a bubble as shown at25'. The position and the degree of inflation of the gob of film-formingmaterial or size of the bubble 25 of film-forming material relative tothe open end of he bag 15' may be varied to facilitate the applicationof the adhesive film-forming material to only desired areas of the bagwalls, as more fully described hereafter.

Once a bubble of film-forming material of desired size is formed withinthe bag 15 a pair of tucker plates 27 are urged against opposite walls29 of the bag 15 to pleat the same along preformed crease lines, asshown at 31. Concomitantly with this pleating operation, opposing walls33 of the bag 15 are gradually moved toward each other by pressureplates 35 to ultimately close the bag. As the opposing walls 29 and 33of the bag 15 are urged against the bubble 25, the inherent plastic orflexible character of the film-forming material and the compressiblenature of the inflating medium permits the bubble 25 to be initiallydistorted into the gradually changing configuration of the open end ofthe bag 15. As best seen in FiGURE 2., during this distortion of thebubble 25, the film-forming material of the bubble wall gradually andprogressively moves along and lines or coats the internal surfaces ofthe portions of the bag walls 29 and 33 with which it engages. Theportions of the bubble wall 25 which are not engaged with the bag walls,such as the top and bottom portions of the bubble, are graduallystretched by the contained inflating medium as it is compressed duringmovement of the bag walls into closed position. Ultimately, thesestretched portions of the bubble 25 are ruptured under the stressesimposed by the compressed inflating medium leaving an adhesive coatingor lining of film-forming material on the internal surfaces of the bagwalls 29 and 33 as shown at 37 in FIGURE 3. At this stage it is merelynecessary to further urge the pressure plates 35 toward each other untilthe adhesively coated bag surfaces are snugly pressed together.

During rupture of the bubble 25, as described above, the portion of thefilm-forming material which remains attached to the nozzle 17 generallycovers the open end thereof and thus prepares the nozzle of subsequentsealing operations. Alternatively, a wiper blade, not shown, may beurged across the free end of the nozzle 17 to remove any excessfilm-forming material attached thereto, after which film-formingmaterial is again delivered through the tube 19 as heretofore described.

As heretofore mentioned, the surface areas of the bag walls 29 and 33lined or coated with the adhesive filmforming material can be accuratelycontrolled by the initial positioning of the free end of the nozzle 17relative to the open end of the bag 15, and the degree of bubbleinflation. in accordance with the above description, during the collapseof the open end of the bag 15, the wall of the bubble of film-formingmaterial is distorted and progressively moves along and lines theinternal surfaces of the bag walls with which it engages until bubblerupture occurs. Thus, with the free end of the nozzle 17 positionedslightly above or within the open end of the bag 15, the appliedadhesive coating or lining of film-forming material generally extends tothe uppermost edges of the bag walls. Alternatively, when the nozzle isprojected well into the open end of the container, the adhesive liningof film-forming material applied to the internal surfaces of the bagwalls terminates inwardly of the bag, leaving the internal bag surfacesdirectly adjacent to the uppermost edges or" the bag walls uncoated. Itwill, of course, be apparent that the width of this uncoated portion ofthe internal bag surfaces will vary with the extent to which the nozzle17 is projected into the bag 15.

The degree of inflation of the gob of film-forming material relative tothe size of the open end of the bag 15 primarily determines the area ofthe internal surfaces of the bag walls which are coated or lined withthe adhesive film-forming material. Thus, where a relatively wide sealis required, the gob of film-forming material may be expanded until theresulting bubble 25 engages with and, if desired, progressively linesportions of the internal surfaces of the bag Walls 29 and 33.Alternatively, the mass of film-frming material may be expanded to forma bubble 25 which is smaller than the open end of the bag 15. With thislatter procedure, the internal surfaces of the bag walls 29 and 33 wouldengage with the bubble 25 after the open end of the bag has beenpartially collapsed, or only during the terminal stage of the collapsingoperation, to thus limit the area of the bag internal surfaces whichengage with and are lined with the adhesive filmforming material beforethe bubble is ruptured.

The method of the present invention is not limited for use with specificbag or container constructions, or by the particular procedures employedin effecting collapse of the open ends of the various forms ofcontainers. Thus, as shown in FIGURES 4 and a gob 41 of film-formingmaterial carried by a nozzle 43 may be positioned adjacent to the openend of a filled bag 45 as it is supported by cooperating grippers 47 and49. In much the same manner as described with reference to FIGURES l-3,the gob 41 of film-forming material is expanded within the open end ofthe bag 45 as a bubble 51 of desired size. Relative movement is theninitiated between the filled portion of the bag 45 and the bagsupporting grippers 47 and 49 to twist the bag at the area 53- withinwhich the bubble 51 is located as shown in FIGURE 5. During thistwisting operation, the bubble 51 is deformed and progressively lines orcoats the internal surfaces of the bag until bubble rupture isoccasioned. As heretofore described, the position and size of the bubble51 relative to the open end of the bag 45 may be varied to control thearea of the bag wall which is adhesively coated.

With relatively large containers or containers having elongated openends, scaling is best achieved as shown in FIGURES -6 and 7. With thepreferred procedure illustrated in FIGURE 6, a nozzle 55, similar to thenozzle 17 heretofore described, is positioned within or slightly abovethe open end of a container 57 and adjacent to one of its side walls 59.A gob of film-forming material is provided at the tip of the nozzle 55,in a manner as heretofore described, and is then expanded into a bubble61. As the bubble 61 contacts with and adheres to the adjacent containerwall 59, the nozzle 55' and container 57 are moved relative to eachother concomitantly with the continued expansion of the film-formingmaterial to provide a bubble 61 across the open end of the container. Toassure that the wall thickness of the bubble is substantially the samealong its entire length, the film-forming material is preferablydelivered to the free end of the nozzle 55 at a uniform ratecontinuously with the expansion thereof. The open end of the container57 may be then collapsed or 6 pleated and closed in the same manner asdescribed with reference to FIGURES 1-3.

With the arrangement illustrated in FIGURE 7, a series of nozzles 63 areemployed in providing a plurality of bubbles 65 01" film-fonmingmaterial Within the open end of a container 67. The nozzles 61 aresimilar to the nozzles 17 in construction and function, each including aduct 69 for delivering film-forming material from a common supplyconduit 71, and a duct 73 for an expanding or inflating medium alsosupplied from a common conduit 75. Alternate nozzles '63 are preferablyprojected to at least two different levels within the open end of thecontainer 67 to position the resulting bubbles 65 in staggeredrelationship. Thus, as the bubbles 65 are ruptured upon the collapse ofthe open end of the container full assurance is provided that all.desired interior surfaces of the container walls are lined with anunbroken coating of adhesive film-fonming material.

Added advantage of the present invention is that the method may becarried out under sub-atmospheric conditions. Thus, where it isdesirable or necessary to remove air or other gases from the containerand material being packaged, a gob of film-forming material may bepartially inflated within the open end of a container while suchcontainer is positioned within a sealed chamber, after which the chambermay be evacuated. During the evacuation of the chamber, the partiallyinflated bubble of film-forming material gradually expands and coversthe open end of the container. Final sealing could then be achieved asdescribed with reference to FIGURES 1-3.

While preferred embodiments of the invention have been shown anddescribed, it is to be understood that changes and variations may bemade without departing from the spirit and scope of the invention asdefined in the appended claims.

I claim:

1. A method of sealing an open-ended container after material to bepackaged is inserted therein consisting of the steps of positioning abubble of tacky film-forming material within an open end of thecontainer above the material being packaged, collapsing a portion of thecontainer adjacent to its open end against the bubble so as to rupturethe same and cause the tacky film-forming material thereof to therebyprovide a coating of tacky filmforming material along the internalsurfaces of the collapsed portion of the container, and pressing thecoated surfaces of the container together to bond the same.

2. A method as defined in claim 1 wherein the portion of the containeradjacent to its open end is collapsed by twisting.

3. A method as defined in claim 1 wherein the portion of the containeradjacent to its open end is collapsed by urging opposite walls thereoftoward each other.

4. A method of sealing an open-ended container after material to bepackaged is inserted therein consisting of the steps of positioning abubble of tacky film-forming material within the open end of thecontainer above the material being packaged, gradually collapsing theportion of the container adjacent to its open end to progressivelyengage the internal surfaces of such portion of the container with thebubble of tacky film-forming material, continuing the collapse of saidcontainer portion until the bubble of tacky film-forming material isruptured to cause the tacky film-forming material thereof to therebyprovide an adhesive coating along the internal surfaces of the collapsedportion of the container and pressing the coated surfaces of thecontainer together to bond the same.

5. A method of sealing an open-ended container after material to bepackaged is inserted therein consisting of the steps of positioning amass of tacky film-forming material Within the open end of the containerabove the material being packaged, expanding the mass of material intothe form of bubble which engages with the internal surfaces of thatportion of the container adjacent to its open end, and collapsing theportion of the container engaged with the bubble so as to rupture thesame and cause the tacky film-forming material thereof to therebyprovide a coating of tacky film-forming material along the internalsurfaces of the collapsed portion of the container, and pressing thecoated surfaces of the container into contacting relationship with eachother.

6. A method as defined in claim wherein expansion of the mass ofmaterial is effected by partially inflating the same and subsequentlyapplying a vacuum to the open end of the container and the partiallyinflated mass of material.

7. A method as defined in claim 5 wherein the portion of the containeradjacent to its open end is collapsed by twisting.

8. A method of sealing a container having an open end of elongatedconfiguration after material to be packaged is inserted thereinconsisting of the steps of disposing a mass of tacky film-formingmaterial within the open end of the container above the material beingpackaged, expanding the mass of tacky film-forming material into theform of a bubble, continuously delivering tacky fihnforming material tothe mass during the expansion thereof, effecting movement of the mass oftacky film-forming material relative to and along the open end of thecontainer concomitantly with the expansion thereof, collapsing theportion of the container adjacent to its open end against the bubble soas to rupture the same and cause the tacky film-forming material thereofto thereby provide a coating of tacky film-forming material along theinternal surfaces of the collapsed portion of the container, andengaging the coated container surfaces to adhesively bond the same.

References Cited in the file of this patent UNITED STATES PATENTS1,422,300 Pape July 11, 1922 2,252,435 Lust Aug. 12, 1941 2,313,643Howard Mar. 9, 1943 2,412,862 Bergstein Dec. 17, 1946 2,532,871 WagnerDec. 5, 1950 2,585,766 Guggenheim Feb. 12, 1952 2,592,081 Toulmin Apr.8, 1952 2,833,096 Randall May 6, 1958 2,872,766 Meissner Feb. 10, 19592,903,833 Jones Sept. 15, 1959 2,907,153 Toles Oct. 6, 1959 2,962,843Hoelzer et a1 Dec. 6, 1960 2,996,858 Swenson Aug. 22, 1961 3,037,897Pelley June 5, 1962

8. A METHOD OF SEALING A CONTAINER HAVING AN OPEN END OF ELONGATEDCONFIGURATION AFTER MATERIAL TO BE PACKAGED IS INSERTED THEREINCONSISTING OF THE STEPS OF DISPOSING A MASS OF TACKY FILM-FORMINGMATERIAL WITHIN THE OPEN END OF THE CONTAINER ABOVE THE MATERIAL BEINGPACKAGED, EXPANDING THE MASS OF TACKY FILM-FORMING MATERIAL INTO THEFORM OF A BUBBLE, CONTINUOUSLY DELIVERING TACKY FILMFORMING MATERIAL TOTHE MASS DURING THE EXPANSION THEREOF, EFFECTING MOVEMENT OF THE MASS OFTACKY FILM-FORMING MATERIAL RELATIVE TO AND ALONG THE OPEN END OF THECONTAINER CONCOMITANTLY WITH THE EXPANSION THEREOF, COLLAPSING THEPORTION OF THE CONTAINER ADJACENT TO ITS OPEN END AGAINST THE BUBBLES SOAS TO RUPTURE THE SAME AND CAUSE THE TACKY FILM-FORMING MATERIAL THEREOFTO THEREBY PROVIDE A COATING OF TACKY FILM-FORMING MATERIAL ALONG THEINTERNAL SURFACES OF THE COLLAPSED PORTION OF THE CONTAINER, ANDENGAGING THE COATED CONTAINER SURFACES TO ADHESIVELY BOND THE SAME.